1. Field of the Invention
The present invention is generally concerned with cable trays, i.e. the U-section troughs used to support, contain and protect electrical cables.
2. Description of the Prior Art
The present invention is more particularly directed to cable trays which are in the form of a trellis of wires, in practise metal wires, joined together in some appropriate manner, in practise by welding, and comprising longitudinal wires usually known as warp wires that run longitudinal and in a rectilinear or quasi-rectilinear manner along all of their length and, transverse to or spaced along these longitudinal wires, U-shaped transverse wires usually called weft wires with the appropriate transverse profile, the combination forming a bottom, in practise a plane bottom, and two plane sides.
Even more particularly, the present invention is directed to cable trays of this kind in which the width measured from one side to the other is equal to at least 150 mm.
For convenience, the wires of these cable trays have until now all had the same cross-section, sometimes with the exception of the edge longitudinal wires of the sides when they are welded in a T-shape to the ends of the transverse wires.
As the wires are in practise of circular cross-section, until now they have usually all had the same diameter, sometimes with the exception of the edge longitudinal wires of the sides, as just mentioned.
The present invention is based on the observation that by varying the cross-section, and thus in practise the diameter, of the wires employed, it is advantageously possible, other things being equal, to reduce the weight of a wire cable tray, and therefore to reduce its cost, without affecting its mechanical strength.